What do ink-jet printers, chainsaws and jet engines have in common? More than you would think, if Chris Harris has his way. After building hundreds of aircraft engines over the years, Harris, owner of Northwest UAV Propulsion Systems in McMinnville, keeps running into the same problem — inconsistent droplet sizes in the fuel stream. But by using Hewlett-Packard ink-jet technology in his new fuel-injection system, he says he can make diesel and other fuels burn 15% to 20% more efficiently. Decreasing the amount of partially burned large droplets eventually could lower emissions and improve fuel economy for propeller engines, jets and more common appliances. “The key is getting the droplet size small enough for a clean burn,” Harris says. After purchasing five patents from HP in May, Harris, former HP developer John da Cunha, and a research team from the Microproducts Breakthrough Institute in Corvallis developed a prototype engine only four months later. He says there are kinks to work out such as altitude, vibration and shock, but Harris says his quarter-size device could be applied to a variety of small engines, chainsaws included. “We’re just trying to make small motors run well,” Harris says.